Chapter 1 General introduction Wouter Jacobs* and Anton Vonk Noordegraaf* Department of Pulmonology, VU University Medical Center, Amsterdam * Chapter 1 In 1865 The German physician Klob reported autopsy findings of a patient who had developed progressive ankle oedema , dyspnoea and cyanosis prior to his death at 59. In stead of the cardiac pathology he expected, Klob found an impressive narrowing of the finer branches of the pulmonary artery with localised arteriosclerosis.1 In 1891 Romberg described a similar clinical course in a 24-year old patient.2 Other than the abnormalities in the pulmonary vessels he also noted a massive right ventricular hypertrophy. This disease now known as Pulmonary Arterial Hypertension (PAH) is a rare disease with an estimated incidence of 1-2/million inhabitants per year for the idiopathic form.3-5 Reported prevalence of PAH in patients with connective tissue disease varies from 2-50%6-16 and it can be detected in 0,5% of HIV patients.17-18 By consensus pulmonary hypertension is defined by a mean pulmonary artery pressure greater than 25mmHg. Pulmonary hypertension may arise due to various underlying alternative conditions and the clinician must have an understanding of the context in which PH occurs as different treatment strategies may be necessary in different situations. The clinical substrates of PH have been catalogued based on their pathological characteristics, clinical presentations, hemodynamic profiles and therapeutic outcomes into 5 different groups. The current classification of PH was provided by consensus at a world symposium of PH specialists held in Venice 2003 and is shown in table 1.19 PAH is defined as pulmonary hypertension classified in group 1 according to the Venice classification and is either idiopathic or from the associated etiologies mentioned. When examining PAH histopathology characteristics of PH with atheromatous changes, dilation of large pulmonary arteries and medial hypertrophy and remodelling of muscular arteries are found. If pulmonary hypertension persists right ventricular hypertrophy, dilation and ultimately failure are common sequelae. Besides these histopathologic features common to all causes of Pulmonary Hypertension, each of the forms of Pulmonary Arterial Hypertension are associated with characteristic lesions involving both the pre-acinar and intra-acinar arteries. These include constrictive lesions at the vessel intima, remodelling of the media or adventitia, as well as complex (plexiform) lesions involving changes of the entire vessel wall. In addition to constrictive and complex lesions, thrombosis of small vessels is noted frequently in the absence of evidence to suggest an embolic source. 20 A diagnosis of PAH portends a dismal prognosis and before the advent of PAH specific therapies median survival of IPAH patients was estimated at 2.8 years.21 The discovery of prostacyclin I2, in 1976 by Moncada and Vane22 was the first step in the development of PAH specific therapies and currently there are three different classes of PAH specific drug therapies which are well established. They are the prostanoids, the endothelin receptor antagonists and the phosphodiesterase type 5 inhibitors and target three different pathways involved in abnormal contraction and proliferation of smooth muscle cells.23 The development of these PAH specific therapies has improved survival.24,25 However long-term survival in the modern management era remains poor26 and knowledge on combining these drug therapies is limited. Currently the prostacyclin I2 analogue epoprostenol is widely perceived as the most potent PAH 10 General introduction The Venice classification of pulmonary hypertension19 Chapter 1 Table 1 1. Pulmonary Arterial Hypertension (PAH) 1.1 Idiopathic (IPAH) 1.2 Familial (FPAH) 1.3 Associated with (APAH): 1.3.1 Collagen vascular disease 1.3.2 Congenital systemic-to-pulmonary shunts 1.3.3 Portal hypertension 1.3.4 HIV infection 1.3.5 Drugs and toxins related 1.3.6 Other (thyroid disorders, glycogen storage disease, Gaucher’s disease, hereditary hemorrhagic teleangiectasia, hemoglobinopathies, chronic myeloproliferative disorders, splenectomy) 1.4 Associated with significant venous or capillary involvement 1.4.1 Pulmonary veno-occlusive disease (PVOD) 1.4.2 Pulmonary capillary hemangiomatosis (PCH) 1.5 Persistent pulmonary hypertension of the newborn 2. Pulmonary hypertension with left heart disease 2.1 Left sided atrial or ventricular heart disease 2.2 Left sided valvular heart disease 3. Pulmonary hypertension associated with lung diseases and/or hypoxaemia 3.1 Chronic obstructive pulmonary disease 3.2 Interstitial lung disease 3.3 Sleep-disordered breathing 3.4 Alveolar hypoventilation disorders 3.5 Chronic exposure to high altitude 3.6 Developmental abnormalities 4. Pulmonary hypertension due to chronic thrombotic and/or embolic disease (CTEPH) 4.1 Thromboembolic obstruction of proximal pulmonary arteries 4.2 Thromboembolic obstruction of distal pulmonary arteries 4.3 Non-thrombotic pulmonary embolism (tumor, parasites, foreign material) 5. Miscelaneous Sarcoidosis, Histiocytosis X, Lymphangiomatosis, compression of pulmonary vessels (adenopathy, tumor, fibrosing mediastinitis) specific drug therapy available27 and data corroborating this are reviewed in Chapter 2. However prostanoid adminstration, either intravenous, subcutaneous or by inhalation, can be bothersome, and the possibility of oral therapy with either an endothelin receptor antagonist or a phosphodiesterase-type 5 inhibitor is an attractive alternative. Aim of this thesis is to describe long-term treatment results in idiopathic PAH patients treated at the VU University Medical Centre, a referral centre for PAH patients in the Netherlands. Different treatment strategies were used in different time periods. Untill 2002 the only PAH specific therapy available in the Netherlands was i.v. epoprostenol. In Chapter 3 we describe treatment results with our current treatment strategy which 11 Chapter 1 involves first-line oral therapy with the endothelin receptor antagonist bosentan and subsequently addition of alternative PAH specific therapies as needed. Treatment results in these patients are compared with our historical cohort of patients treated with first-line i.v. epoprostenol. Subsequently in Chapter 4 we describe efficacy of prostanoids added to oral therapy after treatment failure on first line therapy. In Chapter 5 we sought to determine causes of differential treatment effects between sexes using invasive haemodynamic and cardiac MRI follow-up measurements. In recent years PAH awareness has improved amongst physicians in the community and this has lead to increasing patient referrals. In Chapter 6 we consider a predictive model capable of identifying left diastolic heart failure as a differential cause of pulmonary hypertension in these patients; obviating the need for right heart catheterisation. To conclude we summarize current understanding of PAH specific drug treatments and discuss future prospects in chapter 7. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 12 Klob J. Endarteriitis pulmonalis deformans. Wien Wochenbl 1865;31:45. Romberg E. Über sklerose der lungen arterie. Dtsch Arch Klin Med 1891;48:197-206. 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A Doppler echocardiographic study of 135 Japanese patients. Chest 1997;111:36-43. Koh ET, Lee P, Gladman DD, Abu-Shakra M. Pulmonary hypertension in systemic sclerosis: an analysis of 17 patients. Br J Rheumatol 1996;35:989-93. Ungerer RG, Tashkin DP, Furst D, Clements PJ, Gong H, Jr., Bein M, et al. Prevalence and clinical correlates of pulmonary arterial hypertension in progressive systemic sclerosis. Am J Med 1983;75:6574. Yamane K, Ihn H, Asano Y, Yazawa N, Kubo M, Kikuchi K, et al. Clinical and laboratory features of scleroderma patients with pulmonary hypertension. Rheumatology (Oxford) 2000;39:1269-71. Morgan C, Knight C, Lunt M, Black CM, Silman AJ. Predictors of end stage lung disease in a cohort of patients with scleroderma. Ann Rheum Dis 2003;62:146-50. Pan TL, Thumboo J, Boey ML. Primary and secondary pulmonary hypertension in systemic lupus erythematosus. Lupus 2000;9:338-42. Asherson RA, Higenbottam TW, Dinh Xuan AT, Khamashta MA, Hughes GR. Pulmonary hypertension in a lupus clinic: experience with twenty-four patients. J Rheumatol 1990;17:1292-8. Alpert MA, Goldberg SH, Singsen BH, Durham JB, Sharp GC, Ahmad M, et al. Cardiovascular manifestations of mixed connective tissue disease in adults. Circulation 1983;68:1182. 16. Hosoda Y, Suzuki Y, Takano M, Tojo T, Homma M. Mixed connective tissue disease with pulmonary hypertension: a clinical and pathological study. J Rheumatol 1987;14:826-30. 17. Nunes H, Humbert M, Sitbon O, Morse JH, Deng Z, Knowles JA, et al. Prognostic Factors for survival in human immunodeficiency virus-associated pulmonary arterial hypertension. Am J Respir Crit Care Med 2003;167:1433. 18. Humbert M, Nunes H, Sitbon O, Parent F, Herve P, Simonneau G. Risk factors for pulmonary arterial hypertension. Clin.Chest Med 2001;22:459-75. 19. Simmoneau G, Galiè N, Rubin L. et al. Clinical classification of pulmonary hypertension. J Am Coll Cardiol 2004;43, supplement 1(12):S5-S12. 20. Tiachman DB, Snow JL, Pietra GG. Histopathology of Pulmonary Arterial Hypertension. In: Taichman DB, Mandel J, editors: Pulmonary vascular disease, Philadelphia, 2006, Elsevrie Inc, pp 20-32. 21. D’alonzo GE, Barst RJ, Ayres SM, et al. Survival in patients with primary pulmonary hypertension. Results from a national prospective registry. Ann Intern Med 1991;115:343-349. 22. Moncada S, Gryglewski R, Bunting S, et al. An enzyme isolated from arteries transforms prostaglandin endoperoxides to an unstable substance that inhibits platelet aggregation. Nature 1976;263,663-665. 23. Humbert M, Sitbon O and Simmonneau G. Treatment of pulmonary arterial hypertension. N Eng J Med 2004;351:1425-1436. 24. McLaughlin VV, Shillington and Rich S. Survival in primary pulmonary hypertension: the impact of epoprostenol therapy. Circ 2002;106:1477-1482. 25. McLaughlin VV, Sitbon O, Badesch DB, et al. Survival with first-line bosentan in patients with primary pulmonary hypertension. Eur Respir J 2005;25:244-249. 26. Survival in patients with idiopathic, familial and anorexigen associated pulmonary arterial hypertension in the modern management era. Circulation 2010;122:156-163. 27. Badesch DB, Abman SH, Simmonneau G, et al. Medical therapy for pulmonary arterial hypertension: updated ACCP evidence-based clinical practice guidelines. Chest 2007;131:1917-1928. 13 Chapter 1 General introduction
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